An Indian hawker sleeps in his cart full of lime juice preparations, early 22 May 2005 in Ahmedabad, capital city of India's western state of Gujarat, as the country is reeling under extreme heat conditions, with night temperatures remaining above the 30 degree Celcius mark. AFP Photo.

The toll since the heatwave bore down on India in early June touched 183 with the number of deaths in the eastern state of Bihar rising to 21 on Sunday, officials said.

At least 39 and 37 people have died from the heat in the sizzling plains of northern Uttar Pradesh and the eastern state of West Bengal while another 11 people died in western Maharashtra and southern Andhra Pradesh states.

Revenue Minister Manmohan Samal said 75 people had died in the eastern state of Orissa.

With temperatures touching 51.1 C (123.9 F), West Bengal's Purulia district on Sunday was India's hottest zone and hundreds of people were reported sick with sunstroke.

"Heatwave conditions also prevailed over parts of (central) Madhya Pradesh, northwest Rajasthan and Maharashtra," the weather office said in a report on its website.

It said the rains had "further advanced" from southern India to reach the central and eastern states as well as parts of Maharastra at the weekend.

The office also predicted heavy rain in the eastern states of Arunachal Pradesh, Assam, Manipur, Mizoram, Meghalaya and Nagaland.

The monsoon, which drenches the subcontinent from June to September and is key to the agriculture-dependent economy, normally progresses steadily north from the southwestern state of Kerala -- allowing farmers to sow summer crops.